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PubMed1993

A mortality study among mild steel and stainless steel welders.

A mortality study was carried out in conjunction with the European mortality study among welders coordinated by the International Agency for Research on Cancer (IARC). The study was aimed at assessing risks for lung cancer in relation to exposure to asbestos, welding fumes containing chromium and nickel, and tobacco smoke. The study included a cohort of 2721 welders and an internal comparison group of 6683 manual workers employed in 13 factories in France. The mortality of the two cohorts was studied from 1975 to 1988 by the historical prospective method. Job histories of welders were traced including welding processes used, metals welded, and proportion of worktime spent in welding. Data on smoking habits were collected from medical records. The observed number of deaths were compared with those expected (standardised mortality ratio (SMR)) based on national rates with adjustments for age, sex, and calendar time. The smoking habits of 87% of the whole study population were known. The distribution of welders and controls according to smoking was not statistically different. The overall mortality was slightly higher for welders (SMR = 1.02, 95% confidence interval (95% CI) 0.89-1.18) than for controls (SMR = 0.91, 95% CI 0.84-0.99). For lung cancer, the SMR was 1.24 (95% CI 0.75-1.94) for welders, whereas the corresponding value was lower for controls (SMR = 0.94, 95% CI 0.68-1.26). The SMR for lung cancer was 1.59 among non-shipyard mild steel welders (95% CI 0.73-3.02). This contrasted with the results for all stainless steel welders (SMR = 0.92, 95% CI 0.19-2.69), and for stainless steel welders predominantly exposed to chromium VI (SMR = 1.03, 95% CI 0.12-3.71). Moreover, SMRs for lung cancer for mild steel welders tended to increase with duration of exposure and time since first exposure, leading to significant excesses for duration > or = 20 years and latency > or = 20 years. Such a pattern was not found for stainless steel welders.

Asbestos↗
PubMed1986

Metallurgical analysis of failed Björk-Shiley cardiac valve prostheses.

An investigation into the mechanisms of failure of current Björk-Shiley cardiac valve prostheses is reported. Two failed valves, one apparently unfailed but defective valve, and one unused valve, were examined by scanning electron microscopy and metallographic section. In the first two valves (removed 12 and 23 months after implantation) fracture was associated with the welds joining the short strut to the valve ring. The fracture surfaces in all cases were heavily faceted and showed branching cracks. Extensive wear had occurred on one fracture surface in the first case, suggesting that one leg of the short strut had failed before the other, though this had been clinically undetectable. The third valve was removed owing to failure of the suturing (24 months after implantation) but one leg of the short strut was found to be completely fractured. The other leg showed extensive cracking and porosity in the weld region. A metallographic section taken through the weld region of the fourth (unused) valve illustrated several sizable defects directly attributable to the welding process. It is suggested that the valves failed by fatigue and that these problems could be overcome if the complete valve cage were machined as a single piece.

Aged↗
PubMed2005

Correlates of oxidative stress and free-radical activity in serum from asymptomatic shipyard welders.

RATIONALE: Oxidative stress is believed to play a key role in the development of welding-induced disease. OBJECTIVES: This study investigated the effects of welding fume exposure on correlates of oxidative stress in the serum of asymptomatic shipyard welders. METHODS: Blood samples from 197 male welders and 150 unexposed male office workers were analyzed for manganese and lead. Serum was assayed for protein, albumin, total antioxidant status (TAS), manganese superoxide dismutase (Mn-SOD), aconitase, glutathione peroxidase (GPx), heat shock protein 70, isoprostane, and reactive oxygen species, using electron spin resonance and chemiluminescence. Comparisons between welders and control subjects on biomarkers of oxidative stress were made, and evaluated for the effects of age and smoking. Associations between blood levels of manganese and lead and biomarkers were also explored. RESULTS: Welding was associated with increases in serum protein, GPx, aconitase, TAS, and isoprostane levels compared with control subjects. These group differences were not altered by age or smoking. In welders and control subjects, age was significantly associated with changes in albumin, TAS, chemiluminescence, GPx, and Mn-SOD. In welders and control subjects, smoking resulted in a decrease in GPx, and in a significant interaction between smoking and chemiluminescence. There were significant correlations between manganese levels in welders' blood and chemiluminescence, GPx, and Mn-SOD, and between lead levels and albumin, TAS, GPx, and Mn-SOD. CONCLUSIONS: These results document that exposure to welding can cause changes in serum biomarkers of oxidative stress that may be valuable in clinical monitoring of disease development and in assessing whether further reduction of worker exposures is needed.

Adult↗
PubMed1990

Fertility among Danish male welders.

Welding may be detrimental to the male reproductive system. Fertility was examined in a Danish cohort of 3702 male metalworkers over a follow-up of 47 674 person-years. Occupational histories were gathered by postal questionnaires. Information on births was obtained by record linkage to the Danish Central Population Register. Among persons who had ever worked as welders, the probability of having a child was slightly reduced the year after a year of welding exposure, even after control for differences in age, birth cohort, paternal parity, birth of a child in the preceding five years, smoking, and consumption of alcoholic beverages (odds ratio 0.89, 95% confidence interval 0.83-0.97). The reduction in fertility was associated with the welding of mild steel, but not with the welding of stainless steel. These findings are consistent with results of previous studies of time to conception and semen quality in welders.

Adult↗
PubMed1977

Urinary chromium as an indicator of the exposure of welders to chromium.

Five welders working with high alloy Cr-Ni steel and one working with mild steel were followed during one work week. The chromium concentration in air was measured concomitantly with urinary chromium determinations. The water-soluble chromium concentrations in air exceeded 0.05 mg/m3 during welding with coated electrodes, but metal inert-gas (MIG) welding produced much lower concentrations. The proportion of water-soluble hexavalent chromium in the air was usually more than 50% of the total chromium concentration during welding with coated electrodes, whereas less than 10% of the chromium produced during MIG welding was in a water-soluble. Since water-soluble chromium (hexavalent) is the more important biologically, the determination of both water-soluble and water-insoluble chromium concentrations is emphasized instead of the measurement of the total concentration. The urinary chromium concentration proved to be a good indicator of short-term exposure to water-soluble chromium when exposure was above the current threshold limit value of 0.05 mg/m3, concentrations of more than 30 microgram/g of creatinine representing an exposure level higher than the threshold limit value.

Adult↗
PubMed2000

Male-mediated spontaneous abortion among spouses of stainless steel welders.

OBJECTIVES: Male-mediated spontaneous abortion has never been documented for humans. The welding of stainless steel is associated with the pulmonary absorption of hexavalent chromium, which has genotoxic effects on germ cells in rodents. Clinical and early subclinical spontaneous abortions were examined among spouses of stainless-steel welders. METHODS: A cohort of first-pregnancy planners was recruited from members of the union of metal workers and 3 other trade unions. The cohort was followed for 6 menstrual cycles from the cessation of contraceptive use. Altogether, 280 pregnancies were conceived, of which 35 were detected by human chorionic gonadotrophic hormone analysis and did not survive to a clinically recognized pregnancy. Information on exposure was collected prospectively in relation to the outcome and was available for all cycles resulting in a pregnancy. Information on pregnancy outcome was collected for all 245 clinically recognized pregnancies. RESULTS: Increased risk of spontaneous abortion was found for pregnancies with exposure to paternal stainless-steel welding (adjusted relative risk 3.5, 95% confidence interval 1.3-9.1). The results were consistent in analyses of both biochemically and clinically recognized abortions. There was no increased risk for spontaneous abortion in pregnancies with paternal exposure to the welding of metals other than stainless steel. CONCLUSIONS: Male welding of stainless steel was associated with an increased risk of spontaneous abortion in spouses. A mutagenic effect of hexavalent chromium has been found previously in both somatic and germ cells, and the findings could be due to mutations in the male genome.

Abortion, Spontaneous↗
PubMed2004

Respiratory symptoms and lung function change in welders: are they associated with workplace exposures?

AIMS: This study investigates whether work-related respiratory symptoms and acute falls in forced expiratory volume in 1 second (FEV1), previously observed in current welders, are related to measured workplace exposures to total fume and metals. METHODS: At four work sites in New Zealand, changes in pulmonary function (and reported respiratory symptoms) were recorded in 49 welding workers (and 26 non-welders) exposed to welding fume. We also determined the personal breathing zone levels of total fume and various metals. RESULTS: Work-related respiratory symptoms were reported by 26.5% of welders and 11.5% of non-welders. These symptoms were related significantly to their personal breathing zone nickel exposure--with an adjusted odds ratio (OR) and 95% confidence interval [CI] of the high exposure group (compared to a low exposure group of 7.0 [1.3-36.6]). There were non-significant associations with total fume exposure (OR = 2.6, 95% CI 0.6-12.2), and exposure index of greater than 10 years (OR=2.8, 95% CI 0.5-15.0). A fall in FEV1 of at least 5% after 15 minutes of work was significantly associated with aluminium exposure (OR=5.8, 95% CI 1.7-20.6). CONCLUSIONS: Nickel exposure from metal inert gas (MIG) and tungsten inert gas (TIG) welding is associated with work-related respiratory symptoms and aluminium exposure from welding is associated with a fall in FEV1 of at least 5 % after 15 minutes of work.

Adolescent↗
PubMed2003

[Respiratory findings and pulmonary function tests among the welders working for the sugar plant factory].

Industrialization and developments in technology run together with health problems in workers. The aim of this study was to examine the effects of the exposure of welding fume on respiratory system. This study was carried out in 32 welders in the "Sugar Factory" in Ankara. As controls, 39 workers who were not exposed to weld fume were included in the study. A questionnaire about respiratory symptoms and exposure history, and pulmonary function tests were obtained and compared between the groups. The incidence of coughing, sputum and dyspnea was found to be statistically greater in the group of welders (65.6%, 84.4%, 68.8%) compared with the control group (33.3%, 41%, 30.8%) (p< 0.05, p< 0.001, p< 0.01). Coughing alone was present in 72.7% of smoking welders whilst sputum production was present in 90.9%. These rates were found to be lower in ex-smoker welders or the welders who had never smoked. Chronic bronchitis was observed in 21.9% of the welders whereas no cases with chronic bronchitis were found in control group. The difference was statistically significant (p< 0.01). The results of pulmonary function tests were not statistically different in welders and control group. These results indicate that the exposure of weld fumes itself may cause respiratory symptoms particularly related with chronic bronchitis therefore a great caution must be taken when dealing with welding.

Adult↗
PubMed1982

Respiratory status of stainless steel and mild steel welders.

Eighty-three full-time stainless steel and 29 mild steel welders from one shipyard were examined clinically, and their lung function was measured. The stainless steel welders had used both tungsten inert-gas (low-fume concentration) and manual metal-arc (MMA) (high-fume concentration) welding methods. The individual exposure of the welders was estimated based on the time spent doing MMA welding, the amount of retained contaminants in the lungs (magnetopulmography), and urinary chromium excretion. The results suggest that there is a greater prevalence of small airway disease among shipyard mild steel MMA welders than among stainless steel welders. Among the stainless steel welders the impairment of lung function parameters was associated with the MMA welding method. The type of welding, then, is important when the health hazards of welders are studied, and welders cannot be regarded as a single, homogeneous group.

Adult↗
PubMed1980

[Incidence of pneumoconiosis in welders in semiautomatic systems in the light of environmental studies].

Several years' measurements of the concentration of dusts and welding fumes, in one of metallurgic plants revealed the mean dust concentration of 3.6 mg/m2 at automatic welding workplace. At semiautomatic welding in CO2 screening the expected concentrations was 10 mg/m3, single measurements concentrations ranging from 0.6 mg/m3 to 140 mg/m3. A similar mean value was obtained from 6 Provincial Sanitary--Epidemiologic Stations. Analysis of data collected at 9 Provincial Sanitary--Epidemiologic Stations indicated that pneumoconiosis prevalence among welders operating semiautomatic equipment in CO2 screening was not higher than the prevalence among welders using screened electrodes. For dusts and welding fumes, the maximum allowable concentration value has been recommended.

Air Pollutants↗
PubMed1980

[Incorporation of manganese in human hair, a criterion for assessment of exposure].

The capability of bradytrophic tissue to store traces of certain elements was used to drawn conclusions as to occupational exposure, with particular reference being made to human hair. Manganese, present in the form of MnO2 aerosol in weld smoke, is of particular relevance to electric welders. Manganese levels were recorded from hair samples obtained from 254 shipyard welders and 237 control persons, the assay being undertaken by means of the neutron activation analysis. Manganese incorporation in hair of shifyard welders usually was five times as high as that in hair of individuals with no exposure, with shipyard welding being characterised by highly unfavourable space conditions. Correlations were also secured between contamination, on the one hand, and effective welding time per day, job conditions, and welding techniques, on the other. No relationships were found to exist between manganese levels in hair and serum. Manganese assessment from human hair, so far undertaken by neutron activation analysis, is a non-invasive exposure test and, therefore, suitable for identifying particularly endangered electric welders for early prophylactic action.

Environmental Exposure↗
PubMed1997

[Kinetics of cell division in peripheral blood lymphocytes of stainless steel welders].

Stainless steel welders are not potential occupational risk of geno- and cytotoxic exposure to chemical mutagens and carcinogens contained in welding fumes. The studies of biological activity of welding fumes evidence their cytotoxicity which depends on chromium and nickel content. In 20 stainless steel welders exposed to chromium and nickel contained in welding fumes, kinetics of cell division was assessed in the culture of peripheral blood lymphocytes. No significant differences were found in the cell division rates between the group of exposed welders and the controls. In welders who smoke, the number of cells present after 70 hrs in the third mitotic division, was reduced in comparison to smokers in the control group what may be considered as a symptom of cytotoxic effect of a combined exposure to welding fumes and tobacco smoke.

Adult↗
PubMed1998

[A welder with chemical pneumonitis caused by inhalation of zinc fume].

A 61-year-old man with a 32-year occupational history of welding developed malaise, cough, and dyspnea after inhalation of smoke while welding galvanized steel. On admission, peripheral leukocytosis, hypoxemia, and diffuse granular and linear opacities on a chest X-ray were present. The bronchioli were exaggerated in a chest high-resolution CT. Bronchoalveolar lavage revealed mild lymphocytosis and transbronchial lung biopsy showed siderosis and exudation of fibrin and neutrophils into alveolar spaces. The clinical and radiographic findings later improved except for an obstructive disorder on pulmonary function test. The respiratory health hazards associated with welding vary according to the materials and the concentration of inhaled substances. Acute chemical pneumonitis caused by inhalation of zinc fumes (zinc oxide) was accompanied by chronic siderosis in this case. It is well known that metal fume fever commonly occurs when inhaling zinc oxide fumes. However acute chemical pneumonitis after exposure to zinc oxide during welding has been only rarely reported.

Aerosols↗
PubMed1987

Sutureless bowel anastomosis using Nd:YAG laser.

Small bowel anastomoses were performed without sutures by using the Nd:YAG laser to produce welded enterotomies. Optimal energy levels for contact and noncontact laser were determined. Anastomoses produced using five target energy levels between 100 and 500 J were examined. Short-term anastomotic strength of these enterotomies was measured 1 min after the welding. Bursting pressure of the laser welded enterotomies was compared to the bursting pressure of traditional two-layer, inverting, interrupted sutured bowel anastomoses. The overall mean bursting pressure of non-contact-welded enterotomies was 50.6 mmHg. Optimal laser settings determined in this initial phase were then used to produce anastomoses in rabbits which are recovered postoperatively for 1 or 2 weeks in order to examine long-term viability and integrity of the anastomoses. All chronic rabbit preparations recovered without complication. The mean bursting pressure was 200 mmHg, not significantly different from that of uncut bowel or two-layer sutured anastomosis.

Anastomosis, Surgical↗
PubMed1994

A novel, "hidden" penicillin-induced death of staphylococci at high drug concentration, occurring earlier than murosome-mediated killing processes.

In log-phase cells of staphylococci, cultivated under high, "non-lytic" concentrations of penicillin G, there occurred a novel killing process hitherto hidden behind seemingly bacteriostatic effects. Two events are essential for the appearance of this "hidden death": (i) the failure of the dividing cell to deposit enough fibrillar cross-wall material to be welded together, and (ii) a premature ripping up of incomplete cross walls along their splitting system. "Hidden death" started as early as 10-15 min after drug addition, already during the first division cycle. It was the consequence of a loss of cytoplasmic constituents which erupted through peripheral slit-like openings in the incomplete cross walls. The loss resulted either in more or less empty cells or in cell shrinkage. These destructions could be prevented by raising the external osmotic pressure. In contrast, the conventional "non-hidden death" occurred only much later and exclusively during the second division cycle and mainly in those dividing cells, whose nascent cross walls of the first division plane had been welded together. These welding processes at nascent cross walls, resulting in tough connecting bridges between presumptive individual cells, were considered as a morphogenetic tool which protects the cells, so that they can resist the otherwise fatal penicillin-induced damages for at least an additional generation time ("morphogenetic resistance system"). Such welded cells, in the virtual absence of underlying cross-wall material, lost cytoplasm and were killed via ejection through pore-like wall openings or via explosions in the second division plane and after liberation of their murosomes, as it was the case in the presence of low, "lytic" concentrations of penicillin. Bacteriolysis did not cause any of the hitherto known penicillin-induced killing processes.

Bacteriolysis↗
PubMed2006

Evaluation of alveolar clearance by Tc-99m DTPA radioaerosol inhalation scintigraphy in welders.

OBJECTIVES: The welding process produces metal fumes and gases which may affect respiratory health. Technetium-99m diethylenetriaminepentaacetic acid (Tc-99m DTPA) dynamic lung scanning is an easy, noninvasive method to assess disorders of alveolar-capillary barrier permeability secondary to epithelial damage. We aimed to investigate the alveolar clearance by Tc-99m DTPA radioaerosol inhalation scintigraphy in welders, to assess additive effects of exposure to welding fumes and cigarette smoking on clearance rate of alveolar epithelium and to determine the correlation between Tc-99m DTPA aerosol lung scintigraphy and spirometric measurements. METHODS: Nine nonsmoking welders, 9 smoking welders, and a control group of 6 nonsmokers and 6 smokers were accepted to the study. Tc-99m DTPA radioaerosol inhalation scintigraphy was performed in all subjects. Clearance half time (Tl/2) was calculated by placing a monoexponential fit on the curves. Penetration index (PI) was also calculated on the first minute image. Pulmonary function tests of welders and control group were compared. RESULTS: The mean T1/2 values of Tc-99m DTPA of the nonsmoking welders were significantly higher than those of the nonsmoking control group (82.1+/-24.3 min and 48.1+/-9.7 min, respectively; p = 0.003). The mean T1/2 values of Tc-99m DTPA of the smoking welders were higher than those of the smoking control group (53.3+/-24.5 min and 44.5+/-9.7 min, respectively; p = 0.510). PI of the nonsmoking welders was significantly higher than that of the nonsmoking control group (0.46+/-0.38 and 0.39+/-0.46 respectively; p = 0.004). PI of the smoking welders was significantly higher than that of smoking control group (0.43+/-0.38 and 0.37+/-0.45, respectively; p = 0.019). There was a negative correlation between T1/2 value and FEV1% (r = -0.468, p = 0.016), FVC% (r = -0.442, p = 0.024) and FEF25-75% (r = -0.391, p = 0.048) in the welders and control group. No statistically significant differences were found in the values of the standard pulmonary function tests of any of the subjects. CONCLUSIONS: Welding seems to decrease alveolar clearance which causes an increase in the penetration index. This was considered to be due to fibrotic changes and increased number of alveolar macrophages induced by welding fumes.

Adult↗
PubMed1984

Weldability of beta titanium arch wires.

Beta titanium arch wire segments were joined in a variety of configurations by means of four different commercial welders available to the orthodontist. Test specimens were prepared using the point-to-point and flat-to-flat electrode configurations and a range of settings on each welding apparatus. Tension-shear and tension-twist tests were conducted to determine force values to rupture the welded joints; 90 degrees cold-bend tests provided a measure of relative ductility near the joints compared to the as-received wires. Results indicated that the flat-to-flat electrode configuration is preferred for obtaining strong welded joints with low levels of distortion. Optimum settings have been determined for each of the four welders. Microstructural observations of the beta titanium and joint structure are presented; these are correlated with the energy level settings for the welding process.

Dental Alloys↗
PubMed2005

Intermittent and chronic ultraviolet light exposure and uveal melanoma: a meta-analysis.

OBJECTIVE: To examine the association between ultraviolet light exposure and uveal melanoma. DESIGN: Meta-analysis. METHODS: A review of 133 published reports on risk factors for uveal melanoma revealed 12 studies that provided sufficient information to calculate odds ratios (ORs) and standard errors for ultraviolet light exposure factors. Data from these studies were extracted and categorized into intermittent ultraviolet exposure factors (welding, outdoor leisure, photokeratitis) and chronic ultraviolet exposure factors (occupational sunlight exposure, birth latitude, lifetime ultraviolet exposure index). Summary statistics were calculated for all risk factors reported by > or =4 independent studies. MAIN EXPOSURE MEASURES: Welding, outdoor leisure, photokeratitis, occupational sunlight exposure, birth latitude, and lifetime ultraviolet exposure index. RESULTS: For intermittent ultraviolet exposure, welding was found to be a significant risk factor (5 studies, 1137 cases; OR, 2.05 [95% confidence interval [CI], 1.20-3.51]). Outdoor leisure was found to be nonsignificant (4 studies, 1332 cases; OR, 0.86 [95% CI, 0.71-1.04]). Photokeratitis conferred susceptibility in 3 reports studying this variable, but there were too few studies to validate meta-analyses. For chronic ultraviolet exposure, meta-analysis found occupational sunlight exposure to be a borderline nonsignificant risk factor for development of uveal melanoma (4 studies, 572 cases; OR, 1.37 [95% CI, 0.96-1.96]). Latitude of birth was found to be nonsignificant (5 studies, 1765 cases; OR, 1.08 [95% CI, 0.67-1.74]). CONCLUSION: This meta-analysis yielded inconsistent results associating ultraviolet light with development of uveal melanoma. There was evidence implicating welding as a possible risk factor for uveal melanoma.

Environmental Exposure↗